W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 62

• Manufacturer Part Number: W83977AF
• Description: W83877TF Plus Kbc, Cir, RTC
• Manufacturer: Information Storage Devices, Inc

Control Register (ICR). A selected interrupt can be enabled by setting the appropriate bits of this
register to a logical 1.
Bit 7-4: These four bits are always logic 0.
Bit 3: EHSRI. Setting this bit to a logical 1 enables the handshake status register interrupt.
Bit 2: EUSRI. Setting this bit to a logical 1 enables the UART status register interrupt.
Bit 1: ETBREI. Setting this bit to a logical 1 enables the TBR empty interrupt.
Bit 0: ERDRI. Setting this bit to a logical 1 enables the RBR data ready interrupt.
3.2.8
Two 8-bit registers, BLL and BHL, compose a programmable baud generator that uses 24 MHz to
generate a 1.8461 MHz frequency and divides it by a divisor from 1 to 2
the baud generator is the baud rate multiplied by 16, and this is the base frequency for the transmitter
and receiver. The table in the next page illustrates the use of the baud generator with a frequency of
1.8461 MHz. In high-speed UART mode (refer to CR0C bit7 and CR0C bit6), the programmable
baud generator directly uses 24 MHz and the same divisor as the normal speed divisor. In high-
speed mode, the data transmission rate can be as high as 1.5M bps.
3.2.9
This is a temporary register that can be accessed and defined by the user.
Programmable Baud Generator (BLL/BHL) (Read/Write)
User-defined Register (UDR) (Read/Write)
7
0
0
6
5
0
4
0
3
2
1
0
RBR data ready interrupt enable (ERDRI)
TBR empty interrupt enable (ETBREI)
UART receive status interrupt enable (EUSRI)
Handshake status interrupt enable (EHSRI)
W83977F/ W83977AF
Publication Release Date: January 1997
16
-1. The output frequency of
PRELIMINARY
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